Java SDK notes

Posted on 2017-08-20

(1) Generate a random BigInteger in range of [0, 2^(numBits)-1]

BigInteger(int numBits, Random rnd)

Solve “java.lang.OutOfMemoryError: Java heap space”

Posted on 2017-08-08

Use -Xmx to set the maximum heap size (which may use hard drive space as Java heap). e.g. set the max heap size to 10GB:

java -Xmx10g MainClass

It may be further optimized using garbage collectors such ConcurrentMarkSweep:

java -Xmx10g -XX:+UseConcMarkSweepGC MainClass

Posted on 2017-08-03

Disable “duplicated code” detection
- Settings → Editor → Inspections → General → Duplicated Code
- (Or better) in the source code, use @SuppressWarnings(“Duplicates”)
- Ref.: stackoverflow
Show source file structure
1. From menu: “View” -> “Tool Windows” -> “Structure”
2. Quick key: CMD + 7
Reformat all codes under a folder: in Project view, select the folder, then Code -> Reformat Code

Posted on 2017-06-11

echo $(/usr/libexec/java_home)